//Given a binary tree and a sum, determine if the tree has a root-to-leaf path s
//uch that adding up all the values along the path equals the given sum. 
//
// Note: A leaf is a node with no children. 
//
// Example: 
//
// Given the below binary tree and sum = 22, 
//
// 
//      5
//     / \
//    4   8
//   /   / \
//  11  13  4
// /  \      \
//7    2      1
// 
//
// return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22. 
//
// Related Topics Tree Depth-first Search 
// 👍 2233 👎 529

package com.second.leetcode.editor.en;

import com.datastructures.TreeNode;

public class PathSum {
    public static void main(String[] args) {
        Solution solution = new PathSum().new Solution();
    }
    
    //leetcode submit region begin(Prohibit modification and deletion)
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public boolean hasPathSum(TreeNode root, int sum) {
        if (root == null) return false;
        if (root.left == null && root.right == null) {
            if (sum == root.val) return true;
            return false;
        }
        boolean hasPathSumLeft = hasPathSum(root.left, sum - root.val);
        boolean hasPathSumRight = hasPathSum(root.right, sum - root.val);
        return hasPathSumLeft || hasPathSumRight;
    }
}
//leetcode submit region end(Prohibit modification and deletion)

}
